Which of the following is the phenomenon caused when Radio waves travel in two or more paths during propogation and produce slowly-changing phase differences between signals ?

Options

A. Absorption
B. Fading
C. Baffling
D. skip

Explanation

To solve the question regarding the phenomenon caused when radio waves travel in two or more paths during propagation and produce slowly-changing phase differences between signals, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for a phenomenon related to radio waves that travel through multiple paths and result in changing phase differences.

2. **Identifying Key Terms**: The key terms in the question are "radio waves," "travel in two or more paths," and "slowly-changing phase differences."

3. **Analyzing the Options**:
- **Absorption**: This refers to the loss of signal strength as it passes through a medium. It does not describe the multi-path propagation.
- **Fading**: This phenomenon occurs when radio signals experience variations in signal strength due to multiple paths. It is characterized by slowly changing phase differences between signals.
- **Baffling**: This term is not commonly used in the context of radio wave propagation.
- **Skip**: This refers to the reflection of radio waves off the ionosphere, allowing them to travel beyond the horizon. It does not specifically relate to phase differences in multi-path propagation.

4. **Conclusion**: Based on the analysis, the correct answer is **fading**, as it directly relates to the variation in signal strength and phase differences caused by radio waves traveling through multiple paths.

### Final Answer:
The phenomenon caused when radio waves travel in two or more paths during propagation and produce slowly-changing phase differences between signals is **fading**.

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